The present invention relates to a method and apparatus for applying a ring fastener to, for instance, secure a first member to a second member at the point at which the first and second members touch or cross. More particularly, the present invention relates to a method and apparatus for securing first and second members to each other in instances in which the members are difficult to access as, for instance, in the tying of reinforcing steel.
A number of so-called automatic staple guns, hog ring applicators, and devices for applying fasteners are known in the patent literature (see, for instance, U.S. Pat. Nos. 2,174,152, 2,217,840, 3,628,230, 3,810,495, 3,945,238, and 4,003,118). However, for various reasons, the devices described in these patents have not solved the problems of applying a fastener or clip to secure two members to each other in certain applications. For instance, one application which has been problematical is in the tying of the reinforcing steel in concrete walls, columns, piers, mats, slabs, beams, roadway, and paving.
An illustration of the type of problems encountered is provided by a description of the tying of reinforcing steel in concrete roadway. Because such reinforcing steel generally rests on a roadbed, e.g., gravel, dirt, or other surface, the two reinforcing bars to be tied to each other must be lifted up off of that surface so that a wire can be wrapped around the two bars. These operations are generally accomplished manually and are slow and exhausting and therefore, labor intensive. Some specific disadvantages of this method are summarized in the background section of U.S. Pat. No. 3,810,495. Further, the repetitive nature of those operations (e.g., tying every second intersection over a ten mile stretch of highway pavement makes for thousands of ties) gives rise to repetitive trauma disorders such as carpal tunnel syndrome, causing lost work time and production as well as the possibility of permanent physical disability to the worker.
As evidenced by the above-referenced U.S. Pat. No. 3,810,495, the problems associated with the tying of reinforcing steel have been recognized before. Additionally, U.S. Pat. No. 3,477,351 describes a bar tying machine which raises up individual longitudinal bars and applies ties at selected intersections of that bar with a transverse bar. On information and belief, however, the device described in that patent has not found widespread acceptance in the industry, perhaps because of the complexity, and consequent unreliability and cost, of the device.
Another approach to solving these problems, disclosed in U.S. Pat. No. 4,388,791, is to modify the tie used to secure the reinforcing bars at their intersection. That patent describes a U-shaped resilient wire, or clip, the legs of which are bent into a J-shaped configuration when viewed from the side. According to that patent, the clip can be positioned and secured with one hand by a worker who can support the bars with the other hand. Also on information and belief, this device has not been widely utilized in the industry, possibly because it still requires that the bars be lifted up off of the surface on which they rest to allow application of the clip. Further, it is often necessary to remove or adjust a tie after it has been applied, e.g., when improperly placed. In spite of the teaching of resiliency in that patent, such clips must be quite rigid to provide the necessary strength to the connection, and that rigidity makes the clip difficult to remove and/or adjust.
It appears, therefore, that there is still a need for a reliable, low cost device for applying ties or other types of fastener to concrete reinforcing steel and that such a device would be more likely to be considered to solve this problem if it could apply the fastener without requiring that the bars be lifted. In other words, a device is needed which can (a) transport a fastener or clip down around the two bars, (b) "dig" down into the dirt, gravel, or other strata on which the bars rest to apply the fastener around the bars, and (c) retract or otherwise accommodate rapid reloading of another fastener for transport downwardly at the next intersection of two bars. Further, the device needs to be reliable, durable, and adaptable for being powered with a powder charge or with electric, hydraulic, pneumatic, or manual power. It is, therefore, an object of the present invention to provide (1) an apparatus which has all these operating characteristics, (2) a method which is capable of being utilized with an apparatus having these characteristics, and (3) a fastener capable of being used in connection with such an apparatus and method.
Such an apparatus, method, and fastener would have widespread application for tying reinforcing steel in walls, piers, slabs, columns, roadway, and other concrete structures and, outside of the concrete and/or construction industry, in applications such as the upholstery and fencing industries, and in any other application in which two members which cross or touch each other need to be secured to each other. Other objects, and the advantages of the present invention, will be made clear from the following description of presently preferred embodiments of a method practiced and an apparatus constructed in accordance therewith.